CN114762644A

CN114762644A - Action assisting device and driving method thereof

Info

Publication number: CN114762644A
Application number: CN202110233762.6A
Authority: CN
Inventors: 罗富仁; 蓝客愉
Original assignee: Wistron Corp
Current assignee: Wistron Corp
Priority date: 2021-01-04
Filing date: 2021-03-03
Publication date: 2022-07-19
Anticipated expiration: 2041-03-03
Also published as: JP2022105468A; TWI780556B; US20220216816A1; JP7481303B2; TW202228624A; CN114762644B

Abstract

The invention discloses a motion assisting device and a driving method thereof. The action assisting device comprises at least one bracket and a driving device for driving the bracket. The driving device comprises a brushless direct current motor, a rotor angle sensor and a sensing driver. A rotor angle sensor senses an angle of the brushless DC motor. The sensing driver is switched corresponding to the angular speed of the brushless DC motor to estimate a corresponding angle using a corresponding algorithm. The corresponding angle is used as the angle of the brushless direct current motor. The sensing driver is used for driving the brushless direct current motor according to the corresponding angle, so that the brushless direct current motor provides supporting force to the at least one bracket. Therefore, the construction cost of the mobile auxiliary device can be saved, the power consumption can be reduced, and the reliability can be improved.

Description

Action assisting device and driving method thereof

Technical Field

The present invention relates to a driving technique for a mobility assistance device, and more particularly, to a mobility assistance device and a driving method thereof.

Background

Due to the aging of the global population, many elderly people have an increasing demand for their personal care and self-walking, and therefore, mobile assistance devices (or products called exoskeleton assistances/exoskeleton robots, etc.) with better performance and price are being developed.

The mobility assistance device (exoskeleton assistive device/exoskeleton robot) can be worn on a user to perform a movement by assistance force provided by various motors in the mobility assistance device, so as to increase the mobility of the user's limbs (usually lower limbs), for example, to assist the leg muscles to exert force. If so, the selling price of the mobile auxiliary equipment is still high. Therefore, in order to maintain the proper functions of the mobility assistance device while reducing the cost of the mobility assistance device, the most important parts of the mobility assistance device are required to be: the motor device considers how to save the cost and maintain the function.

Mobility assistance devices differ from other devices having motor means in the control requirements of the motor means. Other devices with an electric motor device, such as fans, etc., require the electric motor device to be normally maintained at a constant rotational speed to achieve the desired effect. However, the motor device provided in the mobility assistance device will always vary its rotation speed due to the walking motion and the support of both feet, i.e., the motor device will always be adjusted back and forth between a low rotation speed and a medium rotation speed, and is particularly important for the adjustment of the motor device at the medium and low rotation speeds. Moreover, if the motor device is directly controlled to perform reciprocating adjustment between a low-range rotating speed and a medium-range rotating speed without special design, the motor shaking phenomenon often occurs, so that a user of the auxiliary equipment feels uncomfortable.

Disclosure of Invention

The invention provides a mobile auxiliary device and a driving method thereof, which can obtain more accurate rotor angle to continuously drive a brushless direct current motor by using a corresponding algorithm through the angular speed switching of the corresponding brushless direct current motor, thereby saving the construction cost of the mobile auxiliary device, reducing the power consumption and improving the reliability.

The action assisting device of the embodiment of the invention comprises at least one bracket and a driving device. The driving device drives the at least one support. The driving device comprises a brushless direct current motor, a rotor angle sensor and a sensing driver. The rotor angle sensor senses an angle of the brushless DC motor. The sensing driver is coupled with the rotor angle sensor. The sensing driver switches corresponding to the angular velocity of the brushless DC motor to estimate the corresponding angle using a corresponding algorithm. Wherein the corresponding angle is taken as an angle of the brushless DC motor. The sensing driver is used for driving the brushless direct current motor according to the corresponding angle, so that the brushless direct current motor provides a supporting force to the at least one bracket.

The embodiment of the invention provides a driving method of a mobile auxiliary device. The action assisting device comprises at least one bracket and a driving device for driving the at least one bracket. The driving device comprises a brushless direct current motor. The driving method includes the steps of: sensing the angle of the brushless direct current motor to judge whether the angular speed switching of the brushless direct current motor occurs or not; and estimating a corresponding angle using a corresponding algorithm, corresponding to whether the angular speed switching of the brushless DC motor occurs, wherein the corresponding angle is used as the angle of the brushless DC motor. And driving the brushless direct current motor according to the corresponding angle so that the brushless direct current motor provides a supporting force to the at least one bracket.

Based on the above, the action assisting device and the driving method thereof according to the embodiment of the invention use the corresponding algorithm by switching the angular speed of the corresponding brushless dc motor, for example, a sensorless angle compensation algorithm (also referred to as sensorless control) and a hall sensor angle compensation algorithm for the brushless dc motor are used in a mixed manner. When the rotating speed/angular speed of the brushless direct current motor is low or the brushless direct current motor switches the angular speed from high rotating speed to low rotating speed, the angle of the brushless direct current motor at the moment is calculated by adopting a Hall sensor angle compensation algorithm; when the brushless dc motor has a certain rotation speed, that is, the brushless dc motor performs angular speed switching from a low rotation speed to a high rotation speed, the angle of the brushless dc motor at that time is calculated by using the back electromotive force of the brushless dc motor through a sensorless control technique (that is, a sensorless angle compensation algorithm). And subtracting the angle calculated by the sensorless angle compensation algorithm from the angle calculated by the hall sensor angle compensation algorithm to obtain an angle error value of the two angles, and determining whether the error values of the two angles are too far apart by using a preset sensitivity value (e.g., the angle error value of the two angles is greater than the preset sensitivity value) and adjusting the angle calculated by the hall sensor angle compensation algorithm to be the standard. Therefore, the brushless direct current motor of the embodiment of the invention is not provided with the stepping encoder with the highest accuracy (but is also the most expensive), but is provided with the Hall sensor with lower accuracy and lower cost instead. When the rotation speed of the motor is high (switching of the angular speed from low rotation speed to high rotation speed is performed), the calculation of the rotor angle is changed from the hall sensor angle compensation algorithm to a more accurate sensorless angle compensation algorithm. Therefore, the construction cost of the mobile auxiliary device can be saved, the power consumption can be reduced, and the reliability can be improved. In addition, the embodiment of the invention can provide a driving circuit more accurately by accurately knowing the rotor angle of the motor, thereby reducing the shaking condition of the motor and reducing the uncomfortable feeling felt when using the mobility assistance device.

Drawings

FIG. 1 is a diagram of a mobile assistance device according to an embodiment of the invention.

FIG. 2 is a schematic view of a user, a first brace (thigh brace) and a second brace (shank brace) while the user is walking.

Fig. 3 and fig. 4A to 4B illustrate the relationship between the torque and the rotation speed between the rotor and the stator of the brushless dc motor.

Fig. 5 is a schematic of the exact rotor angle and error angle when hall sensor control is employed.

FIG. 6 is a schematic diagram of a motor device in a mobile assistance apparatus according to an embodiment of the invention.

FIG. 7 is a flowchart illustrating a driving method of a mobile assistant device according to an embodiment of the invention.

Fig. 8 is a detailed flowchart of step S720 in fig. 7.

Fig. 9 is a detailed flowchart of step S840 in fig. 8.

Description of the figures the symbols:

100: a mobility assistance device;

110: a first support;

112, a first side baffle plate;

114. 116, a first strap;

120, a second bracket;

122, a second side baffle plate;

124. 126, a second binding band;

130, a driving device;

210. 220, 230, the posture of the right leg of the user;

310, straight line;

curve 320;

410, a rotor;

420-1 to 420-3, a stator;

510. 520, line segments;

610: a brushless DC motor;

sense driver 620;

630 power stage circuitry;

640, an electronic characteristic sensing circuit;

650, a microprocessor;

VF is vertical to the force application direction;

HF is the horizontal force application direction;

theta is an angle;

f420-1, F420-2 and F420-21;

EA is the error angle;

s710 to S730, S810 to S850, and S910 to S960.

Detailed Description

Fig. 1 is a schematic diagram of a mobile assistance device 100 according to an embodiment of the invention. The user can wear the mobile auxiliary device 100 thereon, which mainly comprises at least one support and a driving device 130 for driving the support. The driving device 130 of the present embodiment is a motor device installed between the supporting frames for providing supporting force for the supporting frames. The driving device 130 of the present embodiment can be disposed at the position of the lower leg of the user. The driving device 130 of the mobility assistance device 100 according to the embodiment of the present invention mainly uses a brushless dc motor (BLDC motor) as a power source to generate an assisting force for the leg of the user. More specifically, the brushless dc motor has characteristics of large torque, small torque ripple, long life …, and the like. In addition, based on the characteristics of energy conservation, heat resistance, easy maintenance and the like of the brushless direct current motor, the brushless direct current motor is widely applied.

In detail, the support of the mobility assistance device 100 includes a first support 110 (e.g., a thigh support applied to a thigh of a user) and a second support 120 (e.g., a lower leg support applied to a lower leg of the user). The first support 110 and the second support 120 are coupled to a driving device 130. The sensing driver in the driving device 130 drives the brushless dc motor in the driving device 130 according to the sensed corresponding angle, so that the brushless dc motor in the driving device 130 provides the supporting force to the first bracket 110 and the second bracket 120, respectively. The mobility assistance device 100 also includes a first side flap 112 (e.g., thigh side flap), at least one first strap (e.g., first straps 114 and 116) (e.g., thigh strap), a second side flap 122 (e.g., calf side flap), and at least one second strap (e.g., second straps 124 and 126) (e.g., calf strap). The first side baffle 112 is fixedly disposed on the first bracket 110.

First straps

114 and 116 are attached to first bracket 110 or first side flap 112. The first side baffle 112 and the

first straps

114 and 116 are used to fix the mobility assistance apparatus 100 to the user's thigh so as to facilitate the user's thigh to be carried when the driving device 130 provides the supporting force to the first bracket 110.

The second side baffle 122 is fixedly disposed on the second bracket 120. The second straps 124 and 126 are connected to the second bracket 120 or the first side flap 122. The second side baffle 122 and the

second straps

124 and 126 are used to secure the mobility assistance device 100 to the user's lower leg to facilitate the movement of the user's lower leg when the driving device 130 provides the supporting force to the second support 120.

When the user wears the mobility assistance apparatus 100 and walks, the user's leg movements are switched back and forth between standing and swinging. Fig. 2 is a schematic view of a user, a first support 110 and a second support 120 when the user walks. The first support 110 and the second support 120 of the right leg of the user and the right motor for providing the right leg supporting force are exemplified in fig. 2. When the user walks forward, the user can stand in a standing position (e.g., the user's right leg position 210 in fig. 2), and the right motor does not need to provide the supporting force between the thigh support and the shank support. Then, from the posture 210 of the user's right leg to the posture 220 of the user's right leg in fig. 2, the left leg is the supporting point and the right leg needs to swing greatly, so the right motor needs to increase the torque of the motor at this time to provide a large supporting force F1 between the thigh support and the shank support. Then, between the user's right leg posture 220 and the user's right leg posture 230 in fig. 2, it is necessary to reduce the torque of the right motor so as to reduce the supporting force thereof to make the leg reach the predetermined ground supporting position, and so on. That is, the motor employed in the mobility assistance device 100 is often required to perform forward and reverse rotation operations under high torque and low rotation speed in a short time.

However, the conventional brushless motors are driven to maintain a fixed rotation speed in the same direction, and do not adjust the rotation speed in a reciprocating manner. Therefore, the application level of the brushless dc motor is different, and there will be substantial difference in the detection technology of the torque and the rotation speed of the brushless dc motor.

The main structure of the brushless motor can be divided into a rotor and a stator. The rotor in this embodiment is implemented by permanent magnets, and the stator in this embodiment is implemented by coils. The brushless direct current motor drives the rotor by changing the magnetic field on the stator, so that the whole motor rotates. The torque and rotation speed detection technique for a brushless dc motor is mainly to detect an angle between a rotor and a stator, because the angle will directly affect the torque and rotation speed of the motor. If the angle between the rotor and the stator cannot be accurately detected or determined, the mobility assistance device 100 may erroneously determine to provide a slightly larger or smaller current when supplying power to the driving device 130, so that the torque and the rotation speed of the driving device 130 are not as expected, which may cause frequent motor vibration and noise of the driving device 130, and a low energy conversion efficiency of the driving device 130, and may cause a user to feel a strong discomfort.

There are many types for detecting an angle between a rotor and a stator of a brushless dc motor, for example, using hall sensors, step encoders, algorithms used for sensorless control, and the like. Fig. 3 and fig. 4A to 4B illustrate the relationship between the torque and the rotation speed and the angle between the rotor and the stator of the brushless dc motor.

The torque, speed and output power of the brushless dc motor can be shown in fig. 3. The X-axis of fig. 3 represents the rotational speed of the brushless dc motor, and is in units of rotational speed per minute (RPM); the left Y-axis of fig. 3 represents the torque of the brushless dc motor in newton-meters (n.m); the Y-axis on the right of fig. 3 represents the output power of the brushless dc motor and has a unit of watt (W). As can be seen from the line 310 in fig. 3, the lower the rotation speed of the motor, the greater the torque output by the motor; the lower the torque output by the motor, and even without torque output, the highest rotational speed of the motor can be obtained, as illustrated by the curve 320 in fig. 3.

In the control technique of the brushless dc motor, the magnetic field on the coil (i.e., the "stator") generates different torque forces due to the position change of the rotor. Fig. 4A and 4B are schematic diagrams illustrating how the position of the rotor changes and the angle between the rotor and the stator affects the torque of the motor. The left half [ A ] of FIG. 4A shows the rotor 410 (i.e., permanent magnet) and the stators 420-1 to 420-3 (i.e., coil) of the brushless DC motor, and the magnetic field of the rotor 410 and the magnetic fields generated by the stators 420-1 to 420-3 intersect at 45 degrees. The right half [ B ] of FIG. 4A shows the magnetic field of the rotor 410 of the brushless DC motor intersecting the magnetic fields generated by the stators 420-1 to 420-3 at 90 degrees. In FIG. 4A, the stators 420-1 to 420-3 are rotated counterclockwise in both directions of the section [ A ] and the section [ B ].

FIG. 4B shows the force application directions of the rotor 410 and the stators 420-1 to 420-3 of the brushless DC motor. The vertical force application direction is labeled VF and the horizontal force application direction is labeled HF. If the magnetic field generated by the stators 420-1 to 420-3 brings the force F420-1 vertically to the rotor 410, the force is completely applied to rotate the rotor 410, and thus the force F420-1 is not consumed unnecessarily. On the other hand, if the magnetic field generated by the stators 420-1 to 420-3 applies the force F420-2 to the rotor 410 in the vertical direction, the force F420-2 is divided into the same force F420-21 in the vertical direction and the other force in the horizontal direction. Only the same force F420-21 in the vertical direction will rotate the rotor 410, so the other force in the horizontal direction will do a virtual work and cause useless consumption. Thus, providing a perpendicular magnetic field to the angle θ provides optimal motor control with accurate knowledge of the rotor 410 angle (or, knowledge of the exact "rotor position").

The present embodiment considers three control techniques for detecting the angle of the rotor 410 of the brushless dc motor, which are encoder (encoder) control, hall sensor control, and sensorless control, respectively. The following are each described briefly.

The encoder control is the best choice for the encoder as the rotor angle sensor of the brushless DC motor under ideal conditions. However, the encoder is expensive, and the encoder has a complicated mechanical structure when it is designed in a brushless dc motor.

The "hall sensor control" is to arrange three hall sensors at intervals of 120 degrees on the brushless dc motor, so as to obtain the position of the rotor. The current rotor angle can be estimated by adding the sampling time and the current angular velocity to the angle sensed by the hall sensor at the last sampling time. Since each state of the hall sensor represents a 60 degree interval, each time the state of the hall sensor changes, it indicates that a 60 degree rotation has been passed. However, the higher the motor speed, the greater the hall sensor speed estimation error will become. Fig. 5 is a schematic of the exact rotor angle (e.g., line 510 of fig. 5) versus the error angle EA (e.g., line 520 of fig. 5) when hall sensor control is employed. As can be seen from fig. 5, the hall sensor angle compensation algorithm at high rotation speed has a large error. When the error becomes large, the current supplied to the motor has large fluctuation, so that the rotor in the motor is not smoothly rotated, and besides energy consumption, vibration and noise are also generated.

The "sensorless control" is because the brushless dc motor generates magnetic induction to the stator (coil winding) due to the rotor (permanent magnet) when rotating. Furthermore, according to lenz's law, when a conductor has magnetic induction, the conductor generates a corresponding back electromotive force. Therefore, the angle information can be reversely deduced by the back electromotive force by utilizing the input voltage and the input current provided for the brushless dc motor and various parameters (such as the equivalent resistance and the equivalent inductance of the motor) in the motor. That is, the sensorless angle compensation algorithm must determine various parameters in the motor and the power conditions (e.g., voltage, current, etc. supplied to the motor) to estimate the back emf. Although the "sensorless control" has high accuracy of the rotor angle, the motor must generate back electromotive force to estimate the rotor angle. Therefore, when the motor is stationary, the rotor angle cannot be estimated.

Therefore, the embodiment of the present invention may estimate the angle of the brushless dc motor using a corresponding algorithm corresponding to the angular speed switching of the brushless dc motor that varies in rotation speed, thereby driving the brushless dc motor using the estimated angle. In detail, when the rotating speed of the brushless direct current motor is low, a hall sensor angle compensation algorithm is adopted to calculate the angle of the brushless direct current motor at the moment; when the brushless dc motor has a certain rotation speed, the angle of the brushless dc motor at that time is calculated by a sensorless control technique (i.e., a sensorless angle compensation algorithm) using the back electromotive force of the brushless dc motor. By using the method to mix the sensorless angle compensation algorithm (also called sensorless control) and the hall sensor angle compensation algorithm of the brushless DC motor, the accurate rotor angle in the motor can be obtained, and further the driving current provided to the motor can be accurately controlled, thereby reducing the jitter of the motor and the uncomfortable feeling when using the mobility assistance device.

Table 1 is an illustration of the rotational speed of the motor, the angle calculated by using the hall sensor angle compensation algorithm (abbreviated as hall algorithm in this embodiment), the angle calculated by using the sensorless angle compensation algorithm (abbreviated as sensorless algorithm in this embodiment), and the output angle of the motor control algorithm that integrates the two algorithms in this embodiment, in accordance with the present invention.

Table 1:

in this embodiment, as can be seen from table 1, when the motor is at a low rotation speed, for example, the rotation speed of the motor is lower than a predetermined rotation speed (for example, 500RPM), the hall algorithm is relatively stable and accurate for detecting the rotor angle of the motor, and there is no problem of algorithm failure. On the other hand, sensorless algorithms have the problem of algorithm failure when the motor is at a low speed (e.g., motor speed less than 500 RPM). The hall algorithm may have a large error in the detection of the rotor angle of the motor when the motor is at a high speed (e.g., the motor speed is above 500 RPM). On the other hand, when the motor is at a high speed (e.g., the motor speed is higher than 500RPM), the sensorless algorithm is more stable and accurate for detecting the rotor angle of the motor. Therefore, when the motor is switched from a low rotating speed to a high rotating speed, the estimation algorithm of the motor rotor angle is switched from the Hall algorithm to the sensorless algorithm. The user can adjust the value of the predetermined rotation speed according to his/her needs, for example, by using experimental data to determine what the predetermined rotation speed is. In other words, when the operation angular velocity of the motor reaches the point where the hall algorithm cannot operate normally (i.e., the difference between the actual angular velocity of the rotor and the angular velocity of the motor is too large), the operation angular velocity is switched to the sensorless algorithm, and the angle estimated by the sensorless algorithm is output as the operation angle of the motor rotor after the switching. In this embodiment, a switched angular speed (e.g., 500RPM as the reference for determining the rotation speed) is designed to ensure that the rotation speed of the motor is high enough to prevent the motor from entering a stop condition.

When the motor is started to switch from a low rotation speed to a high rotation speed, because the angular speed of the rotor is zero, no back electromotive force generates voltage and current, and therefore the operation of a sensorless algorithm cannot be carried out, and therefore the motor start and the estimation of the rotor angle must be carried out by matching a hall sensor with the hall algorithm.

The term "angular speed switching of the brushless dc motor" in this embodiment refers to switching of the brushless dc motor between two conditions of angular speed, that is, one of the two conditions is that the brushless dc motor is switched from a high rotation speed/high angular speed (also referred to as a first rotation speed interval) to a low rotation speed/low angular speed (also referred to as a second rotation speed interval); in another aspect, the brushless dc motor is switched from a low rotation speed/low angular velocity (second rotation speed interval) to a high rotation speed/high angular velocity (first rotation speed interval). The "high rotation speed/high angular velocity" (first rotation speed section) and the "low rotation speed/low angular velocity" (second rotation speed section) can be determined by the predetermined rotation speed. The first rotation speed interval indicates a state in which the rotor angle of the brushless dc motor is detected by a rotor angle sensor (hall sensor) and the detected result is generated, and the angle of the brushless dc motor is greater than the predetermined rotation speed. The second rotation speed interval indicates a state in which the rotor angle of the brushless dc motor is detected by the rotor angle sensor (hall sensor) and the angle of the brushless dc motor is equal to or less than the predetermined rotation speed in the detection result.

However, it is not possible to accurately confirm whether the sensorless algorithm is operating normally by the rotation speed of the motor alone. In order to avoid the situation that the sensorless angle compensation algorithm may not operate normally, the embodiment further subtracts the angle calculated by the sensorless angle compensation algorithm from the angle calculated by the hall sensor angle compensation algorithm to obtain an angle error value of the two angles as a maximum error reference, and determines whether the error values of the two angles are too far apart (e.g., the angle error value of the two angles is greater than a preset sensitivity value) by using a preset sensitivity value, and the adjustment is based on the angle calculated by the hall sensor angle compensation algorithm. That is, when the angle error value is less than or equal to the preset sensitivity value, it indicates that the two angle values calculated by the sensorless angle compensation algorithm and the hall sensor angle compensation algorithm are similar, and the angle value calculated by the sensorless angle compensation algorithm is used as the rotor angle in the motor in this embodiment. On the contrary, when the angle error value is greater than the preset sensitivity value, it indicates that the sensorless angle compensation algorithm may not operate normally, and therefore the angle value calculated by the hall sensor angle compensation algorithm is used as the rotor angle in the motor.

On the other hand, when the motor is switched from a high rotating speed to a low rotating speed, the estimation algorithm for the rotor angle of the motor is switched from a sensorless algorithm to a Hall algorithm. The present embodiment designs a switching angular velocity (e.g., 500RPM as the reference for determining the rotation speed) as a standard for the motor to rotate at a low speed, so as to avoid the abnormal driving of the driver caused by the sudden stop of the motor due to external force or braking when the present embodiment is in the sensorless algorithm. In the embodiment, whether the hall sensor and the corresponding hall algorithm operate normally or not is judged at the same time, so that the normal operation of the sensorless algorithm is ensured.

FIG. 6 is a diagram illustrating a driving apparatus 130 of the mobile assistance device 100 according to an embodiment of the invention. The driving device 130 mainly includes a brushless dc motor 610, a rotor angle sensor (in the embodiment, 3 hall sensors are taken as an example), and a sensing driver 620. The sensing driver 620 is coupled to the rotor angle sensor. The rotor angle sensor (hall sensor) is used to detect the rotor angle in the brushless dc motor 610 and generate a detection result. The driving device 130 may further include a power stage circuit 630, an electronic characteristic sensing circuit 640, and a microprocessor 650. The power stage circuit 630 supplies power to the brushless dc motor 610, the rotor angle sensor (hall sensor), the electronic characteristic sensing circuit 640, and the microprocessor 650 through the current mirror and the power circuit. The electronic characteristic sensing circuit 640 converts the sensing result of the rotor angle sensor (hall sensor) into analog current signals Ia, Ib, and Ic. The microprocessor 650 converts the analog current signals Ia, Ib and Ic into digital signals available to the sensing driver 620.

FIG. 7 is a flowchart illustrating a driving method of a mobile assistant device according to an embodiment of the invention. The driving method of fig. 7 can be applied to the mobility assistance device 100 of fig. 1 and the driving apparatus 130 of fig. 6. Referring to fig. 6 and fig. 7, in step S710, the sensing driver 620 senses an angle of the brushless dc motor 610 to determine whether an angular speed switching of the brushless dc motor 610 occurs. In detail, the hall sensor detects an angle of the brushless dc motor 610 and generates a detection result, for example, a digital signal provided to the sensing driver 620 via the power stage circuit 630, the electronic characteristic sensing circuit 640, and the microprocessor 650 as the aforementioned sensing result. The sensing driver 620 determines whether the current rotation speed of the brushless dc motor 610 exceeds a predetermined rotation speed according to the detection result, thereby determining whether the angular speed switching of the brushless dc motor 610 occurs. In step S720, the sensing driver 620 estimates a corresponding angle corresponding to whether the switching of the brushless dc motor 610 occurs or not by using a corresponding algorithm, wherein the corresponding angle is used as the angle of the brushless dc motor 610 for driving the brushless dc motor 610.

Fig. 8 is a detailed flowchart of step S720 in fig. 7. In step S810, the sensing driver 620 obtains the input current provided to the brushless dc motor 610 from the power stage circuit 630 or the microprocessor 650.

In step S820, the sensing driver 620 estimates a first angle using a first angle compensation algorithm (i.e., a hall sensor angle compensation algorithm). The first angle compensation algorithm (hall sensor angle compensation algorithm) estimates the first angle mainly from the detection result of the rotor angle sensor. In step S830, the sensing driver 620 estimates a second angle using a second angle compensation algorithm (i.e., a sensorless angle compensation algorithm). The second angle compensation algorithm (sensorless angle compensation algorithm) calculates the back emf of the brushless dc motor 610 based on the input current of the brushless dc motor 610 and a plurality of parameters (e.g., equivalent resistance, equivalent inductance, etc.) of the brushless dc motor 610, so as to estimate the second angle. Steps S720 and S730 may be performed either sequentially or in time.

In step S840, the sensing driver 620 determines to use the first angle or the second angle as the angle of the bldc motor 610. The sensing driver 620 of the present embodiment mainly determines whether the current rotation speed of the brushless dc motor 610 exceeds a predetermined rotation speed (e.g., 500RPM) to determine to use the first angle or the second angle as the angle of the brushless dc motor 610. In addition, the sensing driver 620 of the present embodiment can also calculate a current angle error between the first angle and the second angle, and determine whether the current angle error is greater than a predetermined sensitivity, so as to determine to use the first angle or the second angle as the angle in the brushless dc motor 620. In step S850, the sensing driver 620 determines the input current required to be provided according to the angle in the bldc motor 610, thereby driving the bldc motor 610 continuously. For example, a vector control algorithm of the motor can be utilized to convert the three-way current of the stator into a rotor coordinate vector; converting the input current and the control current into a voltage command through a current controller; converting the voltage vector of the rotor into three-way voltage of the stator; and the switching states generated by the inverter algorithm are set by the power stage circuit 630.

Fig. 9 is a detailed flowchart of step S840 in fig. 8. Referring to fig. 6 and 9, in step S910, the sensing driver 620 determines whether the currently used angle compensation algorithm is the first angle compensation algorithm (i.e., the hall sensor angle compensation algorithm). If the step S910 is yes, the method proceeds to step S920, and the sensing driver 620 determines whether the current angle error between the first angle and the second angle is not greater than a predetermined sensitivity and the current rotation speed of the brushless dc motor 610 exceeds a predetermined rotation speed (e.g., 500 RPM). If yes in step S920, the process proceeds to step S925 to change the currently used angle compensation algorithm to the second angle compensation algorithm (sensorless angle compensation algorithm). If one of the steps S920 is "no" (e.g., the current angle error between the first angle and the second angle is smaller than the predetermined sensitivity, or the current rotation speed of the brushless dc motor 610 does not exceed the predetermined rotation speed), the method proceeds to step S940 and the currently used angle compensation algorithm is not adjusted.

If the step S910 is no, the method proceeds to step S930, and the sensing driver 620 determines whether the current angle error between the first angle and the second angle is greater than a predetermined sensitivity, or whether the current rotation speed of the brushless dc motor 610 does not exceed a predetermined rotation speed (e.g., 500 RPM). When one of the steps S930 (the current angle error between the first angle and the second angle is larger than the predetermined sensitivity, or the current rotation speed of the brushless dc motor 610 does not exceed the predetermined rotation speed) is yes, step S935 is proceeded to change the currently used angle compensation algorithm to the first angle compensation algorithm (hall sensor angle compensation algorithm). If the two steps in step S930 are no (e.g., the current angle error between the first angle and the second angle is smaller than the predetermined sensitivity and the current rotation speed of the brushless dc motor 610 exceeds the predetermined rotation speed), the process proceeds to step S940 and the currently used angle compensation algorithm is not adjusted.

In step S940, the sensing driver 620 determines whether the current angle compensation algorithm is the first angle compensation algorithm (hall sensor angle compensation algorithm). If the step S940 is yes, the sensing driver 620 uses the first angle as the angle in the bldc motor 610. If the step S940 is no, the sensing driver 620 uses the second angle as the angle in the brushless dc motor 610. When step S950 or step S9860 ends, the process can return to step S910 to continue.

In summary, the mobility assistance device and the driving method thereof according to the embodiments of the present invention use a sensorless angle compensation algorithm (also referred to as sensorless control) and a hall sensor angle compensation algorithm for the brushless dc motor in a hybrid manner. That is to say, when the rotating speed of the brushless direct current motor is low, the hall sensor angle compensation algorithm is adopted to calculate the angle of the brushless direct current motor at the moment; when the brushless dc motor has a certain rotation speed, the angle of the brushless dc motor at that time is calculated by a sensorless control technique (i.e., a sensorless angle compensation algorithm) using the back electromotive force of the brushless dc motor. And subtracting the angle calculated by the sensorless angle compensation algorithm from the angle calculated by the hall sensor angle compensation algorithm to obtain an angle error value of the two angles, and determining whether the error values of the two angles are too far apart by using a preset sensitivity value (e.g., the angle error value of the two angles is greater than the preset sensitivity value) and adjusting the angle calculated by the hall sensor angle compensation algorithm to be the standard. Therefore, the brushless direct current motor of the embodiment of the invention is not provided with the stepping encoder with the highest accuracy (but is also the most expensive), but is provided with the Hall sensor with lower accuracy and lower cost instead. And when the rotating speed of the motor is higher, the calculation of the rotor angle is changed from a Hall sensor angle compensation algorithm to an accurate sensorless angle compensation algorithm. Therefore, the construction cost of the mobile auxiliary device can be saved, the power consumption can be reduced, and the reliability can be improved. In addition, the embodiment of the invention can provide a driving circuit more accurately by accurately knowing the rotor angle of the motor, thereby reducing the shaking condition of the motor and reducing the uncomfortable feeling felt when using the mobility assistance device.

Claims

1. A mobility assistance device, comprising:

at least one bracket; and

a driving device coupled to the at least one support,

wherein the driving device comprises:

a brushless DC motor;

a rotor angle sensor that senses an angle of the brushless DC motor; and

a sensing driver, coupled to the rotor angle sensor, for estimating a corresponding angle corresponding to the angular speed switching of the brushless DC motor by using a corresponding algorithm, wherein the corresponding angle is an angle of the brushless DC motor, and the sensing driver is configured to drive the brushless DC motor according to the corresponding angle, so that the brushless DC motor provides a supporting force to the at least one bracket.

2. The device of claim 1, wherein the rotor angle sensor detects an angle of the brushless DC motor and generates a detection result, the sensing driver determines whether a current rotation speed of the brushless DC motor exceeds a predetermined rotation speed according to the detection result, so as to determine whether the angular speed switching of the brushless DC motor occurs,

wherein the determining whether the angular velocity switching of the brushless dc motor occurs is:

the sensing driver judges the condition that the angle of the brushless DC motor enters a second rotating speed interval from a first rotating speed interval,

or, the sensing driver determines that the angle of the brushless DC motor enters the second rotation speed interval from the second rotation speed interval,

wherein the first rotation speed interval represents a state in which the angle of the brushless dc motor in the detection result is greater than the predetermined rotation speed, and the second rotation speed interval represents a state in which the angle of the brushless dc motor in the detection result is equal to or less than the predetermined rotation speed.

3. The device of claim 2, wherein the corresponding algorithms include a first angle compensation algorithm that estimates a first angle according to the detection result of the rotor angle sensor and a second angle compensation algorithm that estimates a second angle according to a power supply condition and parameters of the brushless DC motor,

the sensing driver determines whether an angular speed switching of the brushless DC motor occurs, to determine whether the first angle of the first angle compensation algorithm or the second angle of the second angle compensation algorithm is used as the angle of the brushless DC motor, and to drive the brushless DC motor according to the angle of the brushless DC motor.

4. The device of claim 3, wherein the sensing driver further calculates a current angle error between the first angle and the second angle, and determines whether the current angle error is greater than a predetermined sensitivity to determine whether to use the first angle or the second angle as the angle of the brushless DC motor.

5. The device of claim 4, wherein the sensing driver uses the first angle of the first angle compensation algorithm as the angle of the brushless DC motor when the current angle error is greater than the predetermined sensitivity or the current speed of the brushless DC motor does not exceed the predetermined speed,

when the current angle error is not greater than the predetermined sensitivity and a current rotational speed of the brushless DC motor exceeds the predetermined rotational speed, the sensing driver uses the second angle of the second angle compensation algorithm as the angle of the brushless DC motor.

6. The mobility assistance device of claim 1, wherein the rotor angle sensor is a hall sensor.

7. The mobility assistance device of claim 3, wherein the first angle compensation algorithm is a Hall sensor angle compensation algorithm and the second angle compensation algorithm is a sensorless angle compensation algorithm.

8. The mobility assistance device of claim 7, wherein the sensorless angle compensation algorithm calculates a back EMF of the BLDC motor based on an input current of the BLDC motor and a plurality of parameters of the BLDC motor to estimate the second angle,

wherein the sensorless angle compensation algorithm does not estimate the second angle from the detection result of the rotor angle sensor.

9. The mobility assistance device of claim 1, wherein the at least one support comprises:

a first support coupled to the driving device; and

a second bracket coupled to the driving device,

the sensing driver is used for driving the brushless direct current motor according to the corresponding angle, so that the brushless direct current motor respectively provides supporting force to the first support and the second support.

10. The device of claim 9, further comprising:

the first side baffle is fixedly arranged on the first bracket;

at least one first strap connected to the first bracket or the first side baffle;

the second side baffle is fixedly arranged on the second bracket; and

at least one second strap connected to the first bracket or the second side baffle,

wherein the first side flap, the at least one first strap, the second side flap, and the at least one second strap are used to secure the mobility aid to a user.

11. A method for driving a mobility assistance device, the mobility assistance device comprising at least one frame and a driving device coupled to the at least one frame, the driving device comprising a brushless DC motor, wherein the driving method comprises:

sensing the angle of the brushless direct current motor to judge whether the angular speed switching of the brushless direct current motor occurs or not;

estimating a corresponding angle by using a corresponding algorithm according to whether the angular speed switching of the brushless direct current motor occurs, wherein the corresponding angle is used as the angle of the brushless direct current motor; and

and driving the brushless direct current motor according to the corresponding angle so that the brushless direct current motor provides a supporting force to the at least one bracket.

12. The driving method according to claim 11, wherein the step of determining whether the angular speed switching of the brushless dc motor occurs includes:

detecting the angle of the brushless direct current motor and generating a detection result; and

judging whether the current rotating speed of the brushless DC motor exceeds a preset rotating speed according to the detection result so as to judge whether the angular speed switching of the brushless DC motor occurs or not,

wherein the determining whether the angular speed switching of the brushless DC motor occurs is:

judging the condition that the angle of the brushless DC motor enters a second rotating speed range from a first rotating speed range,

or, determining the condition that the angle of the brushless DC motor enters the second rotating speed interval from the second rotating speed interval,

13. The driving method according to claim 12, wherein the corresponding algorithms include a first angle compensation algorithm and a second angle compensation algorithm, the first angle compensation algorithm estimating a first angle based on the detection result of the rotor angle sensor of the brushless DC motor,

wherein, in response to whether an angular velocity switching of the brushless DC motor occurs, the step of estimating the corresponding angle using a corresponding algorithm comprises:

determining whether an angular speed switching of the brushless DC motor occurs to determine whether to use the first angle of the first angle compensation algorithm or a second angle of the second angle compensation algorithm as the angle of the brushless DC motor.

14. The driving method according to claim 13, characterized by further comprising:

calculating a current angle error between the first angle and the second angle; and

judging whether the current angle error is larger than a preset sensitivity or not so as to determine to use the first angle or the second angle as the angle of the brushless direct current motor.

15. The method according to claim 14, wherein the step of determining whether the current angle error is greater than a predetermined sensitivity to determine whether to use the first angle or the second angle as the angle of the brushless dc motor comprises:

using the first angle of the first angle compensation algorithm as the angle of the brushless DC motor when the current angle error is greater than the predetermined sensitivity or the current rotational speed of the brushless DC motor does not exceed the predetermined rotational speed; and

when the current angle error is not greater than the predetermined sensitivity and the current rotational speed of the brushless DC motor exceeds the predetermined rotational speed, using the second angle of the second angle compensation algorithm as the angle of the brushless DC motor.

16. The driving method according to claim 13, wherein the first angle compensation algorithm is a hall sensor angle compensation algorithm and the second angle compensation algorithm is a sensorless angle compensation algorithm.

17. The driving method according to claim 16, wherein the sensorless angle compensation algorithm calculates a back electromotive force of the brushless DC motor from an input current of the brushless DC motor and a plurality of parameters of the brushless DC motor to estimate the second angle,